JPH06317741A - Range finder - Google Patents

Abstract

PURPOSE:To provide a range finder capable of measuring distances of many points in a photographyic screen with high accuracy and having a wide distance measuring range by combinig plural distance measuring systems. CONSTITUTION:Autofocusing(AF) methods of a trigonometrical survey system and a radar system are combined, a light-speed (radar) range finder 2 using the radar system having good resistance to the looseness between light projecting and receiving elements moves a changing part 4 for distance measuring position by controlling an arithmetical control part (CPU) 1, scans a screen and measures the distance of plural points on the screen. The trigonometrical survey device 3 capable of distance measurement to a near distance is fixed and measures the distance on the middle of the screen on which the probability of existence of the object at a near distance is large. This range finder focuses the photographic lens by a focusing part 5 by using the result obtained by means of the light-speed range finder 2 and the trigonometrical survey device 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance measuring device for a camera, and more particularly to a distance measuring method using both a triangular distance measuring method and a radar method.

[0002]

2. Description of the Related Art Generally, camera distance measuring devices are roughly classified into
Two methods are used: an active method in which a signal is projected from a camera to a subject and the reflected signal is used, and a passive method in which the luminance distribution information of the subject is used. Among them, in the active method using an optical signal, a light quantity determination method that uses the intensity of reflected light, a triangulation distance measurement method that uses the incident position of reflected light, and It is classified into three types of radar systems that measure distance using the speed of.

Further, as a high-precision distance measuring device mounted on a camera and capable of preventing a hollow or the like, a type (multi-AF) capable of measuring a distance at a plurality of points on a screen is adopted. When this multi-AF is performed by the active method, it is necessary to project the distance measuring light to a plurality of distance measuring points. For example, as described in Japanese Patent Laid-Open No. 58-201015, A method is known in which as many light emitting elements as the number corresponding to the distance position are prepared, the light emitting elements are sequentially projected, and the distance is measured by a triangular distance measuring method.

[0004]

However, the above-mentioned multi-system has the drawback that the distance measuring points are discrete, the number of elements increases, and the cost increases. It is also possible to move one light emitting element and measure the distance while moving it. However, in the triangular distance measuring method, the positional accuracy variation between the light emitting and receiving elements directly causes the distance measuring error. High-precision AF could not be expected.

Further, the above-described light amount determination method depends on the reflectance of the subject, that is, the result of distance measurement changes depending on whether the subject is wearing white clothes or black clothes, so that the distance measurement with high accuracy is achieved. It was hard to use it.

Further, the radar AF uses the speed of light traveling back and forth, so it is strong against rattling of the element, but it is not good at distance measurement at a short distance, and it is difficult to compensate for the response delay of the circuit. Was not used for AF.

Therefore, the triangulation method and the radar method are
All of the shooting conditions cannot be satisfied by one method, and there are various drawbacks. Therefore, the present invention is
An object of the present invention is to provide a distance measuring device that can combine a plurality of distance measuring methods to measure many points in a shooting screen with high accuracy and has a wide distance measuring range.

[0008]

In order to achieve the above object, the present invention comprises a light projecting means for projecting light onto an object,
Light receiving means for receiving the reflected light from the object, position detecting means for detecting the incident position of the reflected light on the light receiving means, and timing for detecting the incident timing of the reflected light on the light receiving means There is provided a distance measuring device including a detection means and a calculation means for obtaining a distance to the object by the output of at least one of the position detection means and the timing detection means.

Further, first and second light projecting means for projecting light onto the object, and reflected light of the light projected onto the object from the first and second light projecting means are received. Light receiving means, position detecting means for detecting the incident position of the reflected light of the light projected from the first light projecting means on the light receiving means, and reflected light of the light projected from the second light projecting means. A distance measuring device comprising a timing detecting means for detecting an incident timing to the light receiving means, and a computing means for obtaining a distance to the object by an output of at least one of the position detecting means and the timing detecting means. I will provide a.

[0010]

[Function] The distance measuring device having the above-mentioned structure is a combination of the triangulation type and the speed of light (radar) type, and the same point is measured by the triangulation type and the radar type. , And correction calculation of response delay (ΔT _t + ΔT _j ). Furthermore, changing the projection position of the speed-of-light distance measurement, the radar distance measurement around the screen is performed, and the response delay ΔT of the peripheral object is detected for the peripheral object.
_The distance is measured without depending on _t and ΔT _j . As for the distance actually focused by the camera, the closest data is selected from the distance measurement results L _s and L _{p in} the center and the periphery, and focusing is performed based on this closest data.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings. First, FIG. 1 shows an outline of the distance measuring apparatus of the present invention, which will be described. This distance measuring device is a combination of a triangulation distance measuring system and a radar type autofocus (AF), and a light velocity (radar) distance measuring device 2 using a radar system that is strong against rattling between light emitting and receiving elements Control unit (CP
The distance measuring position changing unit 4 is moved under the control of (U) 1 to measure a plurality of points within the scan screen within the screen. Further, the triangulation distance measuring device 3 capable of measuring a distance up to a short distance is fixed, and the distance is measured in the center of the screen where there is a high probability that a subject at a short distance exists. Then, based on the results obtained by the light speed distance measuring device 2 and the triangulation distance measuring device 3, a focusing lens 5 focuses an unillustrated photographing lens.

Now, with reference to FIG. 2, the reason why the triangular distance measuring device is vulnerable to play between elements will be described. In this triangulation device, the driver 12 has an infrared light emitting diode (IRE).
D) 11 is caused to emit light, and the infrared signal light focused from the light projecting lens 10 toward the subject 16 is projected. Then, the reflected signal light from the subject 16 is condensed by the light receiving lens 13 and guided to the light position detecting element (PSD) 14.

The PSD 14 is a semiconductor device that outputs two output currents i ₁ and i ₂ depending on the incident position x of light. The output currents i ₁ and i ₂ are represented as follows by the incident position x of light and the reference numeral in the figure.

[0014]

[Equation 1]

The incident position x of this light is the distance (base image length) s between the principal points of the light emitting / receiving lenses 10 and 13 according to the principle of triangulation.
And the focal length f of the light receiving lens and the subject distance L satisfy the following relationship.

[0016]

[Equation 2] From the expressions (1) and (2), the reciprocal of the distance 1 / L
Is

[0017]

[Equation 3] Becomes The focusing amount k of the taking lens of the camera is proportional to the reciprocal 1 / L.

If the focal lengths of the light projecting and receiving lenses are equal, if the light projecting position shifts by Δx as shown in the figure, the signal light incident position x becomes x + Δx, and the object distance is L.
Instead, it is erroneously determined as the distance La to the subject 16a. Therefore,

[0019]

[Equation 4] Therefore, the error Δ1 / L is

[0020]

[Equation 5] Becomes When s = 45 mm and f = 16 mm, even if Δx is 10 μm,

[0021]

[Equation 6] Becomes If the correct distance L is 10m,

[0022]

[Equation 7] It can be seen that the error is as much as 1.2 m.

As described above, in the triangulation distance measuring device constructed as shown in FIG. 2, a slight positional error between the light emitting and receiving elements causes a large distance measuring error. AFIC
Reference numeral 15 is a circuit for performing an analog operation on the output currents i ₁ and i ₂ of the PSD 14.

Next, with reference to FIG. 3, a radar-type speed-of-light distance measuring device will be described. In this speed-of-light distance measuring device, the distance measuring light is emitted from the IRED 19 driven by the driver 21 and condensed by the light projecting lens 17, and the subject 16
The distance measuring light is projected toward. The signal light reflected from the subject 16 is collected by the light receiving lens 18, and the sensor 20
Be led to. Then, after being amplified by the amplifier 23, a pulse V indicating a signal light incident timing is generated by the waveform shaper 24.
Converted to _OUT . The light emission timing of the driver 21 is controlled by the pulse generator 22.

Then, the pulse V as shown in FIG.
The time difference ΔT between _OUT and the distance measuring light PG is calculated by the time difference measuring device 2
If the measurement is performed at 5, it is possible to measure the speed of light using the speed c of light. Ideally, the following relationship holds between ΔT, the speed of light c, and the distance L.

[0026]

[Equation 8]

However, in reality, since there is a response delay ΔT _{t of} light emission until the driver or IRED emits light, and a response delay ΔT _j of light reception of the sensor, the amplifier, etc., the equation (5) is as follows. Become.

[0028]

[Equation 9]

For example, when a resolution of 10 cm is required, the judgment round trip time is 2 L from c = 3 × 10 ⁸ m / s.
/C=0.7 nsec, but the response delay of these circuits is on the order of 10 n to 100 nsec. However, due to environmental changes such as temperature, an error on the order of 0.1 nsec will occur immediately, and this will result in an error in distance measurement.
As described above, the focusing position of the taking lens of the camera is proportional to 1 / L. Therefore, if 10c
Even with a resolution of m, if the distance to the subject is 1 m,

[0030]

[Equation 10] That is, the value becomes larger than the error of the triangulation shown in the equation (4) ′. However, if the distance to the subject is 10 m,

[0031]

[Equation 11] Therefore, 1/10 of the error of triangulation shown in equation (4) '
It becomes the order accuracy. Therefore, in radar ranging with the same range resolution, the accuracy of short range is significantly deteriorated as compared with the accuracy of long range.

However, as is clear from FIG. 3 and the equation (5), the parameters for the distance between the light emitting and receiving lenses and the position of each element do not need to be considered in the distance measurement calculation. It can be seen that the distance measuring device is strong against a positional error when the light projecting element is made movable.

Further, since the baseline length between the light emitting and receiving lenses is not required, even if the entire unit 2 is scanned and multi-AF is performed as shown in FIG. 4B, the triangular distance measurement shown in FIG. It is more advantageous than the case.

Further, as shown in FIG. 4C, even if only the light projecting element is scanned to measure the distance at each point, the rattling of the element does not lead to deterioration in accuracy, which is more advantageous than the case of the triangular distance measuring. However, as described in the equation (6), ΔT
The problems of _t and ΔT _j are large, and there has been no example of applying radar ranging to a camera.

This embodiment solves this problem by measuring the same point by triangulation and radar distance measurement, and performing a correction calculation of (ΔT _t + ΔT _j ). That is, in the present embodiment, as shown in the flowchart of FIG. 1B, first, the central portion of the screen to be photographed is measured by triangulation to obtain Ls (step S1). Next, the same central distance measuring point is measured by radar distance measurement to obtain ΔT _s (step S
2). When this is calculated by equation (6),

[0036]

[Equation 12] Becomes

Next, the distance measuring position changing unit 4 shown in FIG. 1 (a) changes the light projection position of the speed-of-light (radar) distance measuring device 2 to perform radar distance measurement around the screen to obtain ΔT _p . Obtain (step S3). Then, the subject distance is obtained by the following equation based on the equation (7) (step S4).

[0038]

[Equation 13]

In this way, it becomes possible to measure the distance to the surrounding subject without depending on the response delays ΔT _t and ΔT _j of the light emitting and receiving circuit. Further, as the distance to be actually focused by the camera, the closest data may be selected from the distance measurement results L _s and L _{p in} the center and the periphery, and this is set to L _min (step S5). Based on this L _min , the focusing section 5 is used for focusing (step S6).

In the distance measuring device constructed as described above, even if the light emitting element is scanned to measure the surrounding area and backlash occurs between the light emitting and receiving elements, the speed of the light is not reflected but the incident position of the reflected light. Since it uses, there is no change in accuracy.

In a short-distance shooting scene called macro shooting, the existence probability of the main subject at the center of the screen is
Although it is close to 100%, the distance measurement at the center is performed by triangulation. Therefore, as mentioned above, the distance measurement value of radar distance measurement, which is weak for short distance measurement, is used to focus on macro photography. It doesn't get sweet.

Next, FIG. 5 shows a schematic block configuration as a first embodiment of the present invention and will be described. This distance measuring device is roughly classified into a CPU that controls the entire device, a light velocity (radar) distance measuring unit, and a triangular distance measuring unit.

The radar range finding unit emits the range finding light, the IRED 103, the driver A 102 for driving the IRED 103, the light projecting lens 104 for collecting the emitted range finding light, and the reflection from the subject. The radar AF 113 measures the distance from the light to the subject.

The triangular distance measuring section includes a light projecting element 107 for emitting infrared light and the like, a driver B106 for driving the same, a light projecting lens 108, a light receiving lens 109, and a light receiving element 111.
A preamplifier section 110 and a ratio calculation section 112 which perform calculation for specifying the subject position from the current value obtained by the light receiving element 111.
Composed of and.

Specifically, the distance measuring device has a structure as shown in FIG. In this distance measuring apparatus, the light emitting / receiving lenses 10 and 13 and the light emitting / receiving elements 11 and 14 for triangulation correspond to the components shown in FIG.

The light projecting element (IRED) 11 is driven by a driver B12. Also, a light receiving element (PSD)
The output current of the amplifier 14 is amplified by the preamplifiers 39 and 40, and is input to the ratio calculation circuit 41 for calculating i ₁ / (i ₁ + i ₂ ) described in the equation (1).

The radar distance measuring light emitted from the IRED 19 driven by the driver A 21 is projected onto the subject 16 via the light projecting lens 17. The distance measuring light (reflected light) reflected by the subject 16 is received by the light receiving lens 18
The light is collected by and is incident on the light receiving element 20. The light receiving element 2
For 0, a silicon avalanche diode (APD) having a high-speed response and an internal multiplication function is used. The A.
P. Since D generally requires a bias of 100 V or more, a dedicated booster circuit 36 is provided so that it can be operated by the battery power source of the camera.

The above A. P. The output of D20 is the amplifier 23
And is input to a waveform shaping circuit 24 including a narrow band filter (BPF) 37 and a comparator 38. The output is compared with the output of the pulse generating circuit 22 which determines the drive timing of the driver A21 in the time difference measuring circuit 25.

As the time difference measuring circuit 25, TMC is used.
1004 (1nse developed by Institute of High Energy Physics
c) An LSI or the like capable of measuring the pulse interval with the following accuracy may be applied, or a circuit as shown in FIG. 9 may be used. The light-speed distance measuring light-projecting element 19 is fixed to a movable member 33, and the movable member 33 can be moved in parallel along a rail 31 by a motor 30 and a feed screw 32. The moving position is determined by the switch 34 for detecting the initial position and the rotation speed of the motor.
Can be detected.

With such a configuration, the triangular distance measuring unit can measure one central point from the signal light incident position, and the light speed distance measuring unit changes the distance measuring point from the incident timing of the reflected light. Is possible.

The light receiving element 20 may have a large area so that the reflected light can be received even if the light projecting element is moved, or the light receiving element 20 may be moved similarly to the light projecting element 19. The arithmetic control circuit (CPU) 1 performs these controls. From the distance measurement results thus obtained, the CPU 1
Detects the distance value to the main subject, and the focusing unit 5
Focus with.

FIG. 7B shows an example in which the distance measuring device of FIG. 6 is built in a camera. In the vertical direction on the front of the camera body 50,
The light emitting / receiving lenses 10, 13, 17, and 18 are arranged. In this camera, a taking lens 51, a viewfinder objective window 52, and a release button 53 are provided. Therefore, as shown in FIG. 7A, the light projection spot is scanned in the lateral direction in the finder screen 54 according to the movement of the IRED 19.

Now, the ratio calculation circuit for triangulation shown in FIG. 6 will be described in detail with reference to FIG. In this ratio calculation circuit, the output currents i ₁ and i ₂ of the PSD 14 are
Amplification by 9, 40 and compression diodes 60, 61
Be washed away. The compressed voltage is input by the buffers 62 and 63 to an expansion integration circuit composed of a differential circuit having a common emitter. Further, a constant current source 66 having a switching function of flowing a constant current I ₀ and an integrating capacitor 67 for integrating the collector current of the transistor 65 with i _x are provided. When the diodes 60 and 61 and the NPN transistors 64 and 65 have a pair property, i ₁ , i ₂ and i
The relationship between _x and I ₀ is

[0054]

[Equation 14] Becomes

Prior to the light emission of the IRED 14, the switch 68 which is turned on and off and the current source 66 which is turned on in synchronization with the light emission of the IRED are controlled by a timing circuit 69. Therefore, after the light emission of the IRED 14, a voltage V _OUT1 proportional to i _x in the equation (9) is generated at both ends of the integral c with reference to Vcc.

[0056]

[Equation 15]

Then, the CPU 1 reads the voltage V _OUT1 with the built-in A / D converter and calculates the subject distance L from the equations (9) ′ and (3). FIG. 9A shows an example of a more detailed circuit of the light speed distance measuring circuit shown in FIG.

This light speed distance measuring circuit includes an APD 20, a preamplifier 23, a B.D. P. It is composed of an F37 and a comparator 38. Therefore, the output PL of the pulse generation circuit 22 and the output COMP of the comparator 38, which determine the timing of driving the IRED (not shown), are delayed by the round trip of light and the response delay of the circuit for projecting and receiving light. As shown in, a time delay ΔT occurs.

A pulse corresponding to this time delay ΔT is generated by a logic composed of an inverter 70, an AMD gate 71, etc. If the constant current source 72 is turned on / off a predetermined number of times m by this pulse ΔT, the integral c73 has Figure 9
As shown in (b), a voltage output V _OUT2 proportional to ΔT is generated.

V _OUT2 = m · ΔT · A ₂ (10) where A ₂ is a proportional constant. This integration c is also turned on / off prior to IRED emission, but this control is performed by the timing circuit 75.

The voltage output V _OUT2 is input to the built-in A / D converter by the CPU 1 as in the triangular distance measuring circuit shown in FIG. Then, the CPU 1 obtains the pulse ΔT from the voltage output V _OUT2 , and obtains the subject distance L as described in the equations (5) to (8).

The capacitors 67 and 73 described above are used.
Alternatively, the switches 68 and 74 can be commonly used as shown in FIG. By controlling the distance measuring device as described above with the flowchart shown in FIG. 10, it is possible to provide a new distance measuring device that can measure many points on the screen with high accuracy and has a wide distance measuring range. .

First, the position of the IRED 19 is reset (step S11). Next, the motor 30 is rotated in the reverse direction and stopped when the initial position detection switch 34 is turned on. Then, the variable n representing the distance measuring point such as the number of rotations of the motor is reset (step S112), and IRED1 is set.
9 is emitted, and the output V _{OU of} the speed-of-light distance measuring circuit described in FIG.
_T2 is detected and set as V _OUT2n (step S1)
3).

Next, it is judged whether or not n has reached the maximum value N (step S14), and if it has not reached N (NO),
n is the position of the IRED 19 for performing distance measurement in the center n = c
Is determined (step S15). When the IRED 19 is n = c (YES), the IRED 11 emits light and the output V _OUT1 from the triangulation device is detected (step S16).

In step S15, the IRED 19 sets n =
If not c (NO), the motor 30 is rotated by a predetermined amount in order to move the IRED 19 by a predetermined amount (step S
17), n is incremented (step S18), and the process returns to step S13.

Further, in step S14, the IRED scanning and distance measurement as shown in FIG. 7A are repeated until it is determined that the IRED 19 has moved by the predetermined movement amount.

[0067] Then, (YES) when n becomes the maximum value N in step S14, the resulting V _OUT21 ~V _OUT2N
Of these, the value with the highest output frequency is selected, and this is set as V _x (step S19).

By focusing on the most frequent value, that is, the distance detected most, it is possible to focus on a considerable part of the screen. However, in a scene in which one person is standing in the landscape, the landscape is in focus, so the distance beyond the predetermined distance is ignored. From this V _x and V _OUT2c , ΔT can be _calculated by the equation (10). V obtained when measuring the center of the screen
_{From OUT2c} , the obtained ΔT is ΔT _s, and from V _x , (1
The ΔT obtained by the equation (0) is set as ΔT _p, and the central object distance L calculated by the equation (9) ′ and the equation (3) from the result V _OUT1 obtained by the principle of triangulation in S15. If the equation (8) is used as L _s , the subject distance L _p can be obtained.

When the photographic lens is focused on this subject distance L _p (step S21), the photographic sequence of the distance measuring apparatus of this embodiment ends. In this embodiment, in steps S19 to S21, the distance value detected with the highest frequency is focused, but the closest distance value may be focused as shown in FIG. The above sequence is arithmetically controlled by the CPU 1.

Next, FIG. 11 shows a flow chart showing the operation of the distance measuring apparatus according to the second embodiment of the present invention. As described above, short-distance measurement for a camera is not suitable for the speed of light measurement.

In the second embodiment, when the subject is present in the center of the screen at a short distance, the probability that the subject is the main subject is high. When the distance is shorter than the distance, the peripheral distance measurement by the speed of light is not performed, and the focus is adjusted according to the result of the central triangular distance measurement.
It is a distance measuring device with a countermeasure against time lag.

First, the IRED 11 is caused to emit light in order to perform the triangulation in the central portion of the screen, and the output V _OUT1 described with reference to FIG. 8 is output.
Is input to the CPU 1 (step S31). Next, CP
The U1 calculates the subject distance L _c at the center from the output V _OUT1 by using the equations (9) ′ and (3) (step S32).

Then, it is determined whether the central object distance L _c is closer or farther than 1 m (step S33). When the subject is closer to the central subject distance L _c than 1 m in this determination (Y
ES) and focus on the central object distance L _c , and the process ends (step S34). In this case, the time lag can be short without shifting to other steps.

However, when it is determined in step S33 that the central object distance L _c is 1 m or more (NO), the process shown in FIG.
Similar to the flowchart of (1), the position of the IRED 19 is reset (step S35), and the variable n indicating the position of the IRED 19 is reset (step S36). Then IRE
D19 is caused to emit light, the output V _OUT2 of the speed-of-light distance measuring circuit is detected, and this is set as V _OUT2n (step S37).

Next, it is judged whether or not n has reached the maximum value N (step S38), and if it has not reached N (NO),
In order to move the IRED 19 by a predetermined amount, the motor 30 is rotated by a predetermined amount (step S43), n is incremented (step S44), and the process returns to step S37.

Further, in step S14, until it is determined that the IRED 19 has moved by the predetermined movement amount, the IRED scanning and distance measurement as shown in FIG. The distance is measured at a predetermined point.

Then, according to the determination in step S38,
When n reaches the maximum value N (YES), first, of the obtained V _{OUT21 to} V _OUT2N , the measured value of V _OUT2R or more is invalidated (step S39), and the resulting V is obtained.
Of _{OUT21 to} V _OUT2N , the most frequently output value is selected, and this is set as V _x (step S40). Figure 1
Similar to 0, the subject distance L from V _OUT1 , V _OUT2c , V _x
p is calculated (step S41), the photographing lens is focused on this subject distance L _p (step S42), and the photographing sequence of the distance measuring apparatus of the present embodiment ends.

Next, FIG. 12 shows the structure of a distance measuring device as a third embodiment of the present invention, and will be described. In the third embodiment, unlike the distance measuring device shown in FIG. 6, four light emitting and receiving lenses are not required, and the light receiving element is used in common. However, if the light receiving elements 85 and 86 are made of PSD, high-speed response becomes difficult. Therefore, as shown in FIG.
As shown in FIG. 13, a PIN photodiode or the like having two light-receiving surfaces that are electrically separated is used so that the reflected signal light spot 90 is incident on both elements.

In this distance measuring device, the boundary between these two elements is arranged perpendicularly to the base line length direction, and the spot 90 moves in the base line length direction according to the distance according to the principle of triangulation. , The subject distance can be obtained from the ratio of the outputs of both sensors.

On the light projecting side, the mirror 82 is used to share the light projecting lens, and the light image of the movable IRED 19 is reflected and projected onto the subject. In addition, a window is provided in the center of the mirror 82, from which an IRED for triangulation is provided.
11 is configured to emit light.

These output currents are supplied to the preamplifiers 83 and 84.
6, the preamplifier output is added by the adder circuit 87, and is input to the time difference measuring circuit 25 via the waveform shaping circuit 24 as in FIG. Similarly, the preamplifier 8
If the ratio of the outputs of 3 and 84 is obtained, as described above, the triangulation can be performed. Therefore, the output of the preamplifier is the ratio calculation circuit 41.
And the output from the ratio calculation circuit 41 is input to the CPU 1.

The functions of these components for measuring the distance to each point are the same as those in FIG. 6, but in the third embodiment,
Assuming a camera with a zoom lens, the zoom position (focal length) information output unit 89 is configured so that the zoom position information of the taking lens 88 can be input to the CPU 1.

Referring to the flowchart shown in FIG. 15,
The operation of the distance measuring device thus configured will be described. First, the CPU 1 is controlled by the zoom position information output unit 89.
Detects the zoom information f _L of the zoom position of the lens at the time of shooting (step S51). Then using the output ratio of IRED11,2 split sensors 85 and 86, in the principle of triangulation to determine the object distance L _c of the screen in the center (step S52).

Then, based on the subject distance L _c , it is determined whether or not radar range finding is to be performed (step S53). If the subject range L _c is closer than 1 m (YES), the resolution is poor and radar range finding is difficult. It is determined that it is not suitable, and the subject distance L _c is focused (step S58). In this focusing, the subject existing in the center at a distance of 1 m or less has a high probability of being the main subject, so that the number of out-of-focus photographs does not practically increase.

When it is determined in step S53 that the object distance L _c is longer than 1 m (NO) and radar distance measurement is selected, the zoom lens position information f _L detected by the CPU 1 in step S51 causes It is determined whether the focal length of is on the side of the telephoto lens (step S54).

If the result of this determination is on the telephoto side (YES), since the angle of view to be photographed is narrow, there is a danger of incorrect distance measurement if the distance is measured in the peripheral area of the screen unnecessarily, so step S58.
Branches to performs focusing distance measurement value L _c of the center of the screen.

However, when the result of the determination in step S54 is on the wide angle side (NO), the IRED 19 and the light receiving elements 85 and 8 are provided.
6, and the time difference measuring device 25 and the like are used to perform multipoint AF for distance measurement of a plurality of areas in the screen by radar distance measurement (step S55).

Next, as described in steps S19 and S20 shown in the flowchart of FIG. 10, the main subject distance L _p is selected from the results of the multipoint AF. Then, the main subject distance L _p is focused (step S5).
7).

In the third embodiment, by such an operation, the IRED 19 is provided on the telephoto side of the zoom lens.
Since the light-velocity AF accompanying the scan is not performed, the time lag can be shortened accordingly.

Further, unlike the first embodiment shown in FIG. 6,
Since it is composed of a pair of light emitting and receiving lenses, further miniaturization is possible. Further, in the present embodiment, as the distance measuring method using the speed of light, the circuit example for measuring the pulse delay time shown in FIG.
A method of modulating the distance measuring light and beating it down when receiving light to measure the phase delay may be used instead.

Next, FIG. 16 shows the structure of a distance measuring apparatus as a fourth embodiment according to the present invention, which will be described. Although this range finder has been described in the above-mentioned embodiment as a configuration for scanning the radar AF, it is an example of a configuration utilizing the merit of the next radar AF.

First, the radar AF does not require a ratio calculation unlike the triangulation, and only needs to detect the timing at which light is incident, and is not easily affected by noise. That is, it is suitable for distance measurement up to a long distance.

In this embodiment, the light emitting / receiving system is commonly used.
This is an example that is not a multi-point type. The CPU 1 adopts the output result of triangulation at a short distance and the result of the radar AF at a long distance.

From the above, the distance measuring apparatus of this embodiment is
High accuracy from short distance to long distance by measuring distance at multiple points in the shooting screen by scanning distance at short distance by triangulation method and radar distance measurement at long distance It is possible to measure various distances. Further, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications and applications can be made without departing from the scope of the invention.

[0095]

As described above, according to the present invention,
By combining a plurality of distance measuring methods, it is possible to provide a distance measuring device capable of measuring many points in a shooting screen with high accuracy and having a wide distance measuring range.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration and operation of a distance measuring device according to the present invention.

FIG. 2 is a diagram for explaining the reason why the triangulation distance measuring device is weak against rattling between elements.

FIG. 3 is a diagram for explaining a radar-type speed-of-light distance measuring device.

FIG. 4 is a diagram showing a light emitting / receiving unit for radar distance measurement and triangle distance measurement.

FIG. 5 is a diagram showing a schematic block configuration as a first embodiment of the present invention.

FIG. 6 is a distance measuring device having a configuration specifically shown in FIG. 6 according to the first embodiment.

7 is a diagram showing a configuration example in which the distance measuring device shown in FIG. 6 is built in a camera.

8 is a diagram showing a configuration example of a ratio calculation circuit for triangulation shown in FIG.

9 is a diagram showing a configuration example of the speed-of-light distance measuring circuit shown in FIG. 6 and a timing chart of outputs of respective members.

10 is a flowchart showing an operation of the distance measuring device shown in FIG.

FIG. 11 is a flowchart showing the operation of the distance measuring apparatus as the second embodiment of the present invention.

FIG. 12 is a diagram showing a configuration of a distance measuring device as a third embodiment of the present invention.

FIG. 13 is a diagram showing a light receiving portion including a PIN photodiode or the like having two light receiving surfaces used in the distance measuring apparatus of the third embodiment.

14 is a diagram showing a configuration example of the timing circuit shown in FIG.

15 is a flowchart showing the operation of the distance measuring apparatus of the third embodiment shown in FIG.

FIG. 16 is a diagram showing a configuration of a distance measuring apparatus as a fourth embodiment of the present invention.

[Explanation of symbols]

1, 101 ... Arithmetic control unit (CPU), 2 ... Light velocity (radar) distance measuring device, 3 ... Triangular distance measuring device, 4 ... Distance measuring position changing unit, 5 ... Focus adjusting unit, 10, 17, 104, 108
... Projector lens, 11, 103 ... Infrared light emitting diode (I
RED), 12, 21 ... Driver, 13, 18, 109
... Light receiving lens, 14 ... Optical position detection element (PSD), 15
... AFIC, 16, 16a ... Subject, 19 ... IRED,
20 ... Sensor, 22 ... Pulse generator (PG), 23 ... Amplifier, 24 ... Waveform shaping section, 25 ... Time difference measuring instrument, 102
... driver A, 106 ... driver B, 107 ... light projecting element, 110 ... preamplifier section, 111 ... light receiving element, 112
… Ratio calculation part, 113… Radar AF.

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[Procedure amendment]

[Submission date] July 28, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0022

[Correction method] Change

[Correction content]

[0022]

[Equation 7] It can be seen that the error is as much as 1.2 m.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0047

[Correction method] Change

[Correction content]

The radar distance measuring light emitted from the IRED 19 driven by the driver A 21 is projected onto the subject 16 via the light projecting lens 17. The distance measuring light (reflected light) reflected by the subject 16 is received by the light receiving lens 18
The light is collected by and is incident on the light receiving element 20. The light receiving element 2
For 0, a silicon avalanche diode (APD) having a high-speed response and an internal multiplication function is used. The A.
P. Since D generally requires a bias of 100 V or more, a dedicated booster circuit 36 is provided so that it can be operated by the battery power source of the camera. If this is a camera with a built-in flash, the booster circuit for the flash may be shared.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0056

[Correction method] Change

[Correction content]

[0056]

[Equation 15] However, A ₁ : proportional constant

[Procedure amendment 4]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 14

[Correction method] Change

[Correction content]

FIG. 14

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Claims (5)

[Claims] 1. A light projecting means for projecting light onto an object, a light receiving means for receiving reflected light from the object, and a position detection for detecting an incident position of the reflected light on the light receiving means. Means, timing detecting means for detecting the incident timing of the reflected light on the light receiving means, and computing means for obtaining the distance to the object by the output of at least one of the position detecting means and the timing detecting means. A distance measuring device comprising: 2. The distance measuring apparatus according to claim 1, wherein the output result of the timing detecting means is corrected by the output of the position detecting means. 3. The timing detecting means is controlled by the output of the position detecting means.
Distance measuring device described in. 4. A first and second light projecting means for projecting light onto an object, and a reflected light of the light projected onto the object from the first and second light projecting means. Light receiving means, position detecting means for detecting the incident position of the reflected light of the light projected from the first light projecting means on the light receiving means, and reflected light of the light projected from the second light projecting means. A timing detecting means for detecting a timing of incidence on the light receiving means, and a computing means for obtaining a distance to the object by an output of at least one of the position detecting means and the timing detecting means. Distance measuring device. 5. The distance measuring apparatus according to claim 4, wherein the second light projecting unit projects the light while scanning a predetermined area around the object.